Insulating structure for high-potential condensers



Dec. 15,1925. 1,565,799

W. DUBILIER INSULATING STRUCTURE FOR HIGH POTENTIAL CONDENSERS Original Filed Feb. 18 1921 INVENTOR MALI/7M DUB/LIE]? ATTORNEYS Patented Dec. 15, 1925.

UNITED, STATES PATENT.- OFFICE.

WILLIAM DUBILIER, OF NEW ROCHELLE, NEW YORK, ASSI GNOR TO DUBILIER CON- .DENSEB & RADIO CORPORATION, OF NEW YOB K, N. Y., A-OOBPORATION OF DELA- WARE.

Original application filed February 18, 1921, Serial No. 445,948. Divided and this application filed August INSULATING STBUCTUREiFOB HIGH-POTENTIAL OONDENSERS.

8, 1925. Serial No. 49,063.

To all whom it may concern:

Be it known that I, WILLIAM Dpsimrm, a citizen of the United States, resldlng at New Rochelle, in the county of Westchester and State of New'Yoi-k, have invented certain new and useful Improvements 111 Insulating Structures for High-Potential Condensers, of which the followmg 1s a specification.

The invention has for an object to provide an insulating supporting structure tor conductors'used with high-potential, high-frequency circuits, of such character as to becapable of withstandin long contmuednse under very severeelectric'al condltions, without substantial losses or undue heating or deteriorationdue to other causes such as puncture,-'creepage, and brush discharge or corona effects.

.wherein the above-mentioned features are combined with suflicient mechanical strength and elasticity to,insu1;e that mechanical injuries will be minimized and obv1ated,'such 2 as might arise, for example, from shocks or temperature changes,

The invention also embodies an insulating structure of the above character having a small capacity, and low phase angle, or phase diflerence in order to reduce to safe limits the-energy losses occurring thereln. A further object of theinvention is to provide a vstructure to be utilized with a high-frequency electrical condenser, and

particularly the high-tenslon terminal thereof, for the purpose of enabling the condenser and terminal to operate to the best advantage, when high-frequencies and undamped or continuous wave lengths are 'em loyed.

ther objects and advantages of the in vention will be in part obvious and inpart specifically pointed out in the description hereinafter contained which, taken in con.- nection with the accompanying drawings, discloses a preferred embodiment of. the in- I vention; such embodiment, however, is to be considered merely as illustrative of its principle. In the drawings:

Fig. 1 is a side view of a high-potential condenser container equipped with a terminal structure madein accordance with the Another object is to provide a structure,

invention for the purpose of leading a highpotential terminal through. the cover of the container. Certain parts are broken away -more clearly to show the details of the said structure; and

Figure 2 is a plan view "of the structure shown in Figure 1.

p This application is a division of my c0pend- -.ing application, Serial No. 445,948, for

patent upon insulating structures for hi 'hpotential condenser terminals and the like, filed F ebruary 18th, 1921. a

When condensers are used with radio transmitting sets of the vacuum tube type for example, and the apparatus is' subjected to undamped high-frequency oscillations such severe strains are set up upon the terminal insulation of the condenser that if ordinary means for insulating the terminal be employed, the insulating medium rapidly deteriorates and breaks down due to the effects of the field which existsbetweeu the terminal. and surrounding metal parts, and other causes.

Many other instances also will occur to those skilled in the art in which the diificulty is present of insulating a hi h-tension conductoremployed in highequency and high-potential apparatus under such circuit conditions, especially with continuous waves against which ordinary insulations are either wholly ineffectual or deteriorate rapidly, due to such causes as heating, brush discharge, or corona effects, with the result that the terminal insulation is very unsatisfactory. In the case of insulating materials heretofore used for such purposes, it is found that the insulation tends to de teriorate gradually under the electrical strains, and heats up, due to the energy losses therein, the heatin increasing as the material deteriorates, an the phase angle or phase difi'erence and losses increasing rapidly upon increased temperature, with the result that a multiplication of losses and deterioration takes place with continued use. Furthermore, mechanical difiiculties are encountered in the use of certain insulating materials, such as porcelain, which tend to break or crack during use due to. many causes, for example, shocks due to gun fire on board ship, temperature changes, etc.

According to the present invention, an insulating structure is used of such character as to reduce the ener losses and heat rise as far as possible, th by means of the insulating material employed and the construction of the insulator, and also to avoid deterioration or mechanical injury due to long continued use.

The form of the invention illustrated, is disclosed as adapted and applied to a-hlghpotential condenser, comprlslng a condenser wall through which the high-potential conductor'is to be led, is provided with a relatively large-opening .5, across which is disposed a sheet mica diaphragm or plate 6, the latter being firmly seated against the walls of the opening, for example by means of a metal ring 7 underlying the edges of the diaphragm'and secured in place by means of a plurality of screws 8. Preferably the edges of theTnetal parts'around the diaphragm 6 are somewhat rounded inorder to reduce the tendency toward arcing or brush discharge,

and I also prefer, to taper the'walls of the cover 3awayfromthe condenser unit, as shown 1n Fig. 1, 1n order to provlde a greater electrical spacing of the cover from the parts of the condenserunit which are at a difierent potential therefrom,- and also to provide more spaceto accommodate the terminal structure without bringing the latter too close to the condenser unit.

The diaphragm or plate 6 is of such large extent as to provide a large -creepage'dis-. tance between the Walls of the cover 3 and.

the high-tension conductor or terminal post,

-which will insure against the occurrence of corona along the surfaces of the laminations making up the plate, under'the conditions of use for which the. condenser is designed. That is to say, there is a tendency for corona eflects to take place not only along t'heexterior surfaces of the plate 6, but also. between the laminations thereof, so that the plate should be of relatively large diameter. For example, where the structure is to be used in connection with sustained undamped oscillations of very high-frequency, 'say 100,000 to 1,000,000 cycles at about 10,000

volts, the active radius of the diaphragm or plate 6 should be about one inch or larger.

I also prefer'to interpose between the plate 6 and the high-tension conductor-9 a tube'10,

consisting of Wound. sheet mica, the walls of the tube thus constituting a barrier -between the conductor and the surrounding metal parts, which will prevent breakdown even though the relatively large. extent of diaphragm 6 should prove insufiicient at cer-' tain times. However, the thickness of the tube 10 is, best made small relative to the diameter of the plate, so that the interposition of the tube between the plate and the conconductor which are exposed beyond its ends.

On opposite sides of the diaphragm 6 there are disposed laminated mica'blocks 11 such blocks being of suflicient thickness to providea relatively large electrical spacing between the portions of the conductor 9 which are exposed beyond their ends and the metallic walls of the cover 3. It will thus be seen that a creepage path from the cover 3 to the exposed portions of terminal 9 must necessarily include;;-the surfaces 12 of the mi'cablocks' 11, and'such surfaces being com-"- posed of the 'edgesqof the mica sheets are particularly resistant to creepage. If desired, the surfaces 12 of blocks 11 may also be corrugated to lengthcn'the creepage distance,'as shown in Fig.1. the form shown it will be noted that the creepage path is broken up into two "distinct sur-. faces. That is to say, it includes not only the surfaces 12 of blocks. 11, but also the sides or faces of the mica sheetsmaking up the diaphragm 6, so that any discharge would have to. bridge these two surfaces in series.

It will be noted .of the above character is homogeneous as regards thedielectric or insulating inaterial employed. That is, there is no variation in the characteristics of the insulation such as would tend to concentrate the electrical Sil'0SSOS4) the weaker portions of the structure. The insulator-is composedv entirely of mica, a dielectric material which will not deteriorate with continued use -provided corona effects or brush discharge are overcome, and the energy losses within the insulator structure are very small, I for many,

reasons. One important factor in securing thisresult is the very small capacity of the insulator, due to its structure and the relation of the metal parts associated with it; for example, where the terminal structure is used in combination with a. condeliser'unitsuch as the element 1 of the drawings, the amount of energytaken up by the terminal insulator depends upon the ratio of its cathat terminalstructure which will not heat unduly. -Furthermore,

the mica making up the insulator is mechanically strong, will withstand shocks without injury, and is not liable to be cracked by temperature changes.

It is preferable that the mica blocks 11 and the diaphragm 6 shall be tightly clamped together to prevent internal loosening, as by means of suitable bearing means or members 13 and 14 disposed on the outer faces of the blocks 11, suitable means being provided to draw the bearingmembers together, such as a.nut 15, threaded on the inner end of terminal post 9.

In making up the insulating structure, I

prefer to subject the mica layers thereof to as high pressure as possible to bind the structure into a solid mass, and make the spaces between the laminations as small as practical, and then the whole insulator may be subjected to the action of a melted wax insulating compound, such as paraffin, kanaube, montan, or a mixture of these waxes, to prevent as far as possible subsequent absorption of moisture by the insulator, and to substitute the insulating compound for the air or moisture which otherwise might remain between the mica layers. The impregnating bath may also be supplemented by a vacuum, which will assist in removing air and moisture from the structure, and after the above steps are completed the insulator is preferably subjected to a high pressure, at least in the neighborhood of 1 ton per square inch, in order that as small an amount as possible of wax shall be retained between the layers, and to prevent the loosening up of the insulator. After the bearing members 13; and 1 1' are placed in position, they will act to retain the solidity of the insulator, which is first effected by the above-described steps.

In the form illustrated in Figs. 1 and 2, the external circuit connection of the condenser may be made by means of binding screw 16 passing into a lug 17 on the hearing member 13. I prefer to dispose the binding member 16 at an angle tothe axis of terminal 9, so that any strains exerted on the structure in tightening up the member 16 will not tend unduly to twist orotherwise damage the terminal structure. The diaphragm 6, however, particularly as reinforced bythe blocks 11, is comparatively rugged and not liable to injury in use. It

will be understood that the inner end of the terminal 9 has a suitable connection (not shown) with the condenser unit.

While-mica is preferred as the material for the diaphragm and blocks 11, any other kind of insulation which isv tenacious and not brittle or fragile, and resistant to heat, and has the other properties of mica insulation, is of course to be regarded as the full equivalent thereof.

VVhile-a specific embodiment of the invention has been described, it is obvious that many changes may be made therein without departing from the spirit of the invention,

as defined in the following claims:

Having described my invention, what I believe to be new and desire to secure and protect by Letters Patent of the United States is 1. A condenser comprising a condenser unit enclosed in a container, one wall of said container having a relatively large opening therein, a sheet mica diaphragm disposed across said opening, a terminal for said condenser unit extending through said 'diaphragm, said diaphragm being of suflicient extent to provide a relatively large distance between said terminal and the periphery of the opening, and laminated sheet mica blocks surrounding said terminal and disposed on opposite sides of said diaphragm, said blocks being of such thickness as to provide a relatively large spacing between exposed portions of the terminal and the metallic wall of the container, the edges of the mica sheets forming the side walls of the blocks.

2. A condenser comprising a condenser unit enclosed in a container, said container having a relatively large opening therein and being shaped to provide a relatively large space between said opening, and said condenser unit, a terminal for said condenser unit extending through said opening, and

a sheet mica support for said terminal extending across said opening, said support including sheet mica layers surrounding the terminal and extending into the space between the opening and the condenser unit.

3. A condenser comprising a condenser unit enclosed in a metal container, a metal cover for said container having a relatively large opening therein, a sheet mica dia phragm disposed across such said opening, a clamping ring for holding said diaphragm in position against the edges of said opening, a terminal for'said condenser extending through the central portion of said diaphragm, a sheet mica tube surrounding said terminal, laminated sheet mica blocks surrounding said tube and disposed on opposite sides of said diaphragm, and means carried by said terminal for clamping together said blocks and diaphragm.

4. A condenser comprising a condenser unit enclosed in a container, having a relatively large opening therein, a sheet mica diaphragm disposed across such said opening, a clamping ring for holding said diaphragm in position aorosssaid opening, a terminal for said condenser extending through the central portion of said diaphragm, laminated sheet mica blocks disposed on opposite sides of said diaphragm, and means carried by said terminal for clamping together said blocks and diaphragm.

5. The combination-of a container, a condenser in said container, the container having a relatively large opening, a sheet-mica diaphragm disposed across said opening and secured around the edge thereof, insulating sheet-mica blocks on the opposite faces of said diaphragm, a terminal for said condenser extending through said blocks and said diaphragm and being spaced a material distance from the periphery of said opening at all points, and means on the terminal for clamping the blocks and the diaphragm together.

6. The combination of a container, a condenser in said container, the container having a relatively large opening, a sheet-mica diaphragm disposed across said opening and secured around the edge thereof, insulating sheet-mica blocks on the opposite faces of said diaphragm, a terminal for said condenser extending through said blocks and said diaphragm and being spaced a material distance from the periphery of said opening at all points, and means on the terminal for clamping the blocks and the diaphragm together, at least one of said blocks having transverse peripheral ridges and grooves to increase the extent'of its outer surface.

7. The-combination of a container, a condenser in said container, the container having a relatively large opening, a sheet-mica diaphragm disposed across said opening, an

annular member secured to the container for holding the diaphragm across said opening, insulating sheet-mica blocks engaging the opposite faces of the diaphragm, and a terminal for the condenser extending through the diaphragm and the blocks, and disposed a material distance from all points in the periphery of said opening.

8. The combination of a container, a condenser in said container, the container having a relatively large opening, a sheet-mica diaphragm disposed across said opening, an annular member secured to the container for holding the diaphragm across said opening, insulating sheet-mica blocks engaging the opposite faces of the diaphragm, and a terminal for the condenser extendin through the diaphragm and the blocks, an disposed a material distance from all points in the periphery of said opening, one of said blocks having annular transverse ridges and grooves to increase the extent of its outer surface.

9. The combination of a container having a condenser therein, the' container having a relatively large opening, a sheet-mica diaphragm disposed across said opening, a clamping ring engaging the diaphragm to secure the same to the container around the periphery of the opening, Insulating sheetmica blocks engaging the opposite faces of the diaphragm a terminal for the condenser extending through said blocks and said diaphragm and spaced a material distance from all points in the periphery of said opening, one of said blocks having transverse annular ridge separated by grooves to increase the exterior surface, and means on the terminal to secure the diaphragm and the blocks together.

In testimony WILLIAM D'UBILIER. 

